Without limiting the scope of the invention, its background is described in connection with layered lithium ion battery electrodes and layered lithium ion battery electrode materials.
The miniaturization of portable electronic devices has created a necessity for smaller, lighter, more durable batteries as their power source. To address this need, a lithium ion battery has been developed having a high capacity, small size, and light weight. Generally, the lithium ion battery has electrodes that can occlude and release lithium ions without requiring electrodeposition of lithium metal. The lithium ion can migrate from the anode into the electrolyte and occlude (by intercalation) from the electrolyte at the cathode. The anode is commonly made of a carbonaceous material and the cathode is made of a lithium transition metal oxide.
Although, cathode materials of lithium metal oxides have a theoretical capacity of around 280 mAh/g, the full capacity of these materials cannot be achieved in practice, and only about 140 mAh/g can be used. Furthermore, overcharging results in lithium removal that degrades the cyclability of these materials.
In addition, lithium cobalt oxide and lithium nickel oxide also may undergo a decomposition reaction on overcharge. For example, layered LiNi0.5O2 transforms to the spinel LiNi2O4 on heating to above 200° C.; at about 245° C., the delithiated material also experiences significant oxygen generation and heat liberation due to decomposition.